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Figure 5.20. Examples of DNA damage induced by radiation and chemicals.

Figure 5.20Examples of DNA damage induced by radiation and chemicals

(A) UV light induces the formation of pyrimidine dimers, in which two adjacent pyrimidines (e.g., thymines) are joined by a cyclobutane ring structure. (B) Alkylation is the addition of methyl or ethyl groups to various positions on the DNA bases. In this example, alkylation of the O6 position of guanine results in formation of O6-methylguanine. (C) Many carcinogens (e.g., benzo-(a)pyrene) react with DNA bases, resulting in the addition of large bulky chemical groups to the DNA molecule.

From: DNA Repair

Cover of The Cell
The Cell: A Molecular Approach. 2nd edition.
Cooper GM.
Sunderland (MA): Sinauer Associates; 2000.
Copyright © 2000, Geoffrey M Cooper.

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